Electric furnace for fixing nitrogen from the air.



S.. BARFQED. ELECTRIC FURNACE FOR FIXING NITROGEN FROM THE AIR. APPLICATION mit) JAN. la. 1916.

I1,232,11 79. Y Patented July 3, 1917.

o 21a* 2 -f- 1 2g T2* 5 19 l' 24 27 5 STATES PATENT OFFICE-.

` svsNn 3mois), or oAlxLAND, cnn-0am f A summon Fon mxING NITROGEN Enom rnnam.- i Speeicationof Letters Patent.

Y Application med January 19,1916.' sex-mlm. 72,939.

To all concern.' l Referring ttov the drawings in detail, A Beit. known that, I, SVEND BABFOED, ja mdicates the furnace proper constructed of citizen of the United States, residing at Oakany suitable make of fire brick or otherl re- Vdate contact with an electric' arc.

land, in the county of Alameda and State of fractory material. Formed interior of the California, have invented new and useful refractory lining A is a furnace chamber 2 Improvements in Electric Furnaces for'Fixinto which 'projects a pair of electrodes 3 ing-Nitrogen from the Air, of which the foland Ll. The electrode 3 is preferably solid lowingfis a specification. Y and constructed of c'op er, steel or any other This invention relates to an electric furmetal desired. The e ectrode is preferably nace particularly constructed for use in con rmade 1n sections which are adapted to be 'Patented July-3, 1917.

nection with the .xation of atmosphericv Yjoined together by a connection similar lto nitrogen, for combining oxygen and nitrothe oneindica-ted at 5 and meansl have furgen, or for the treatmentof other gases by thermore been providedl forV rotating the means of an electric arc. f j electrode and simultaneously forcing it into It is known that certaingaseous chemical the furnace chamber 2 at a rate which is just compounds, such' as oxids of nitrogenf are v`'Siicient to maintain a fixed spacing between formed by passing air through or into immeelectrodes as burning 'away or consumption Many of the electrodes takes place. One Aform of attempts have been made Yto produce commechanism is here s hown for the purpose of pounds of this nature, such as nitro en, rotatmg and feedlng the electrode, said nitric-acid, etc.,` on a commercial scale, ut mechanism comprises a hollow sleeve on the theseattempts have proved more or less un- ,exterior surface of which is formed an annubeingas follows:

successful, the main difficulties lar rack bar 6. Secured on the upper end ofy thesleeve 1s a spur gear? whlch intermeshes. No furnace has seemingly been produced With an elongated p1n1on 8, continuously which is capable of continuous operation, driven by means of a pair of connected bevencountered nor has, any furnace been produced 1n which the air or gases when heated to a high t em perature by the arc is suiciently rapidlyT cooled. It is known that the gaseous chemieled gears 9 and a motor 10. The motor 10 wlth connected gear train, transmits a roelectrode 3 passes, and the second Vmotor 11 cal compounds formed at hightemperatures forces vthe s leeve and electrode in .a downeasily decompose if they are not rapidly ward dlrectlonthrough means of the gear cooled from the high temperature at which tram 12wh1ch inter-meshes with the annular they are formed, to a 'comparatively low rack bar 6. By referring to Flg. 1, it will temperature. Practical experience and operbe seen that the lower electrode 4 is simitary motion to the sleeve through which the ation of furnaces heretofore in use -have also larly controlled and that a pit 14 has been brought out many mechanical diiiiculties provided, to permit insertion of the lower which further renders the process or appaelectrode through the sleeve 6. The lower ratus used mpracticable and commercially electrode' may be constructed in a manner unsuccessful. A similar to the upper electrode 3 or may con- The object of the present invention 1s to sist of metallic oxids compressed into a metal provide a furnace which is so constructed tube which may be constructed so that it can that continuous operation during extended be handled or inserted through the sleeve 6.

- periods of time, OI' instance, thirty days, Whileboth electrodes are here shown as proviously referred to will be entirely overcome.

will be possible, and that the objections previded,` with means for rotating and forcing same 'into the furnace, it is obvious that both The invention consists of the parts and oreither may remain stationary.

the construction and combination of parts Surrounding the furnace A and spaced asA hereinafter more fully described and from'same to form a surrounding air chamclaimed, having reference to the accompanyber, is a metal casing 15. This casing suping drawings in which- Figure l is a central vertlcal sectlon through the furnace.

Fig. 2 is a cross-section online 2-2 of Fig. l..

Fig. 3 is a cross sectlon on line 3-3 of lFig. 1.

ports the refractory material of which the furnace proper is constructed and is itself is therefore insulated from the casing 15 and from the lower electrode 't as this is in turn insulated lfrom the casing 15 by means of an insulating plate 18 similar to that indicated by plate 16. The cooler employed in the present instance is cup-shaped as shown, for reasons hereinafter to be described and 'is provided withv an annular discharge passage 19, which communicates Awith the furnace chamber 2 by means of a centrally disposed downwardly turned cone-shaped neck 20. The annular passage 19 is Vcompletely surrounded or water-jacketed on bothsides and a constant circulation in the Jacket is maintained, through pipes 22 land 23, which are connected with a source of water supply by means of pipe 21. By referring to Fig. 1, -it will also be seen that the annular discharge passage 19 gradually tapers from oneA end to the other, being smallest in area at the upper end. This forms one of the im- `portant features of the present invention and will later lbe more fully described. Centrally disposed in the lower portion of the cooler B, and projecting into the neck 20 or lower end of the discharge passage 19, is a waterjacketed tube 24C, through which the electrode 3 passes. This tube is provided for the purpose of guiding .the electrode 3 and also for the purpose of -cooling same` Pipes 25 and 26 connected with the main supply pipe 21y and the return 21a provide means for keeping aconstant circulation in the tube. The tube is furthermore provided with a stufling box 27 at its upper end, which positively prevents any escape of gases between the electrode and the tube 24. The lower electrode is'also provided with a cooling tube 24;a and a constant circulation of water is maintained through pipes 24".

Formed in the refractory lining A of the furnace is a plurality of air passages 30 which communicate at one end with the interior of the furnace and at the other end with the space formed between the casing 15 and the exterior of the furnace. Said passages are all tangentially disposed and some of the passages are arranged in a horizontal, others in a vertical, and still others in an angular, position. Air admitted tothe space between the casing 15 and the furnace proper, passes through the several passages 30 just described, directly into the furnace chamber 2 and are here given a swirling motion as all the passages are tangentially dis- .posed The air may be Isupplied by any suitable means such as a compressor,l fan, etc., said air being admitted through pipe 31. The provision of the exterior air chamber furnace and the arrangement of the several air passages 30, also forms one of the 1mportantfeatures of the present invention bs will hereinafter be described.

The operation of the furnace as a whole will be as follows :A i f The entering air or gas to ,be treated delivered through pipe 31by means of a compressor or fan, first enters the-space 40 between the furnace A and the casing 15. It then passes through the furnace lining, that is, through the numerous air passages formed therein, the position of which are such that the entering gas or air stream is set ,into a helical motion over the entire inner surface of the lining, preferably this helical motion is downward and inward toward the center of the furnace until the air or gasl stream reaches the circumference of the lower elec-` downward-inward stream and deflects it in an upward-inward direction; 5to facilitate the motion or direction of the air or gas in this manner, the furnace walls are designed with the object in view to create as little disturbance in the air orA gas stream as possible. The upward-inward deflection forces the air or gas into the sphere Yof action of the electric arc and is thus heated to a sufficiently high temperature to cause fixation of the nitrogen contained therein. Y

It is now necessary to cool the resultant product as rapidly as possible to prevent decomposition. This is readily accom-- plished in the present instance by the arrangement and construction of the cooler B. The cooler is so designed and arranged that the air or gas under high temperature after passing through or leaving the arc formed between the electrodes is directed into the neck 20 of the annular discharge passage 19 and Aas this is cone-shaped and flared asshown, but small resistance is offered to the passage'of Ithe hot gases. The gas products impinging with a swirling motion against the metal surfaces of the water-cooled cooler will consequently rapidly decrease in temperature and volume. The velocity is however, kept constant as the annual passage 19 gradually decreases in area as previously described, toward its upper end in proportion to 'the contraction of the gases, thus maintaining a constant velocity, both of in# coming and outgoing gases. is desirable for rapid cooling as the rate of heat transfer from a hot gas toa metallic and cooled surface, being almost directly proportional to the velocity of the gas over this surface is thereby greatly increased. The control and direction of the air currents entering the furnace is of great benefit as it prevents gases already fixed, from decomposing by contacting with the excessively This condition hot furnace walls. These excessive hotfwallsj.v4 of one sideof the stream and not sui- Y.

treated in the furnace. In actual practiceA are however, eliminated in the present in-l stance as the refractory lining is kept comparatively cool ,bythe numerous air `passages formed herein, vandalso'b the 4swirling. action of the incoming air tween the arc and the surface lining. The gases passing through the'annular passage`l9 arefinally permitted to escape through'a pair of pipes indicated at 42 and 43, which .are connectedl with apparatus not necessarily mit's the provision of' a large cooling sur- .face employed for the purpose of rapidly reducing the temperature of the gases' with furnaces heretofore constructed, it has been'found that the best results are obtained-V where continuous operation is possible. -The inelicient fixation.

' described, where the gases are further4 provision 'and arrangement of the solid electrodes here shown that c-an be joined `to new ones, permitsy these to be continuousl fed into the furnace as lthey are consume., without interruptingthe operation of the furnace. The operation may therefore eX-y tend over, practically speaking7 Aan' indefinite period of time, and' all danger of puncturing or burning the electrodes unevenl is entirely eliminated. In several of the rnaces now used, it is common practice to employ hollow metal tube electrodes, closed at the lower ends bymeans of metal caps.-

These tubes are cooled by water entering through a pipey which is centrally vdisposed in the tube and reaches nearly to the capfor the purpose of pcrmittin the. cooling Huid to impinge on same, there y producing the greatest cooling efficiency possible. This cap is however, gradually consumed by the action of the electric arc and it is only a matter of time before it becomes so thin that it punctures, thus not only destroying n the action of the arc but also permitting water to enter the furnace with consequent detrimental action. In my furnace this objection is entirely eliminated as the solid electrodes employed' are easily cooled by means of the tubes 24 instead of internally,

as described. The solid metal electrode, preferably constructed of copper, is passed through the fluid cooled tube 24, which is suiiciently long to guide the electrode and to produce the desired cooling surface required. This, together with the meansfor joining one electrode to the other, and the means `for vrotating and forcing the electrodes inwardly as they are being consumed, not only permits continuous operation over indefinite periods of time, but also prevents the ends of the electrodes from burning un- `evenly, which is objectionable as it often defiects the air stream, causing excessive heatcient heating of the other side, resulting lin Thehelical air .stream passing overthe furnace. walls also keeps the refractory v1ining at such a temperaturethatits insulating value against the passage of the electric v current is maintained, permitting the use of higher. voltages in furnaces of 'large.capac ity where it becomes important to work with as low amperage as practicable in order to reduce the dimensions of/the current carryving parts of the furnace:

Having thus described'my invention, what I.. claim and desire to secure by Letters 'Pat-.

ent is 1. The;combination-with an'electric furnace having al pairl ofelectrodes mountedl therein and asource of: current -s'upply for maintainin an. arc 'between thev electrodes,

of means or delivering air or gas to thel furnace and directing it through the sphere of action of the arc'and a cooler having an annular cooler discharge passage of large area comparedto itsvolume formed therein directly connected With the furnace to rapidly decrease the, temperature of the air or gas after it leaves the electric arc.

2. The combination with an electric furnace having a pair of electrodes mounted therein and a-Asource of current supply for maintaining an arc between the electrodes,

of means for 'delivering-*air or gas to .the furnace and directing it through the sphere of action of the arc, and a cup-shaped cooler having an annular discharge passage of large area compared to its volume formed therein directly connected with the furnace to rapidly decrease the. temperature of the air or gas after it leaves the electric arc.

3. The combination with an electric furnace having a pair of electrodes mounted therein of means for delivering air or gas to the furnace and directing it through the sphere of 'action of the arc, a cup-shaped cooler having a water-jacketed discharge passage of large areacompared to its volume formed therein directly connected with the furnace to rapidly decrease the temperature of the air or gas after it leaves the electric arc, and means for maintaining a circula# 'tion of water in the jacket.

4. The combination with an electric furnace and the electrodes mounted therein,

of means for rotating both electrodes to maintain a uniform heating and reaction in said furnace.

6. The combination with an electric furmaintain a uniform f7' The Combination.with an' electric furnace and the electrodes mounted therein, of

in said furnace. y

nace having means for delivering air or gas thereto and ar'outlet for the gases, of

a cup-shaped cooler having al water-jacketed annular discharge passage of large area formed therein directly connected with the outlet in the furnace, a Water-cooled Qtube centrally disposed and extending throughl the lower end' of the cooler, an electrode extending through said tube into the furnace and adapted to be cooled and guided .by the tube, and a second electrode extending into the furnace.

S. The combination with an electric fur.

nace having means for` delivering air or gas thereto andA an outlet for the gases, of a cupshaped cooler -having a water-jacketedannular discharge passage of Y large area' formed therein directly connected with the outlet in the furnace, a water-cooled tube centrallyl disposed and extending through the lower end of the cooler, an electrode eX- tending through said tube into the furnace and adapted to be cooled and guided by the tube, a second water-cooled tube entering' through the furnace, and an electrode extending through vsaid tube into the furnace.

9. The combination withan electric furnace having means for delivering air or gas thereto and an outlet for the gases, of a cupshaped cooler having a'water-jacketed annular discharge passage of large area formed therein directly connected with the outlet in the furnace, a water-cooled tube centrally disposed and extending through the lower end of the cooler, an electrode extending through said tube into the furnace and adapted to be cooled and guided by the tube, another electrode extending into said furnace, and means for rotating the first named electrode.

10. The combination with an electric furnace having means for delivering air or gas thereto and an outlet for the gases, of a cupshaped cooler having a water-jacketed annular discharge passage Aof large area formed therein directly connected with the l outletiin the furnace, a water-cooled tube centrally disposed and extending through the lower end of the cooler, an electrode 4extending through said tube into the furnace and adapted to be cooled and guided by the nacehaving a plurality of vertically', horizontally and angularly disposed air inlet `passages into a furnace chamber, of a casing surrounding the furnace and spaced from same to form a surrounding air passage which communlcates with. sald chamber through the air inlet passage in the furnace,

and means for delivering air. to be treated to sa1d surrounding air passage. i

12. An electric furnace for effecting gasy reactions comprising a furnace chamber having a substantially concave bottom, an electrode extending into said chamber near the center ofthe concavity, and means for distributing incoming gases over the concave surface of the chamber and directing them generally toward said electrode.

413. An electric furnace for effecting gas reactions comprising a furnace chamber, electrodesextending into said chamber, said chamberbeing provided withan outlet and a plurality of inlets for gases so disposed as to cause part of the incoming gases to move toward said outletY in' contact with, the arc maintained between the electrodes.

14. An electric furnace for effecting gas reactions comprising a furnace chamber providedV with an outlet forgases, an electrode extending into said chamber near said outlet, another electrode extending into said chamber, and means for causing gases to move first near the surface of said chamber and subsequently through the 4center of said chamber in the general direction of the line joining said electrodes.

first away from said outlet and subsequently 15. In an electric furnace for effectinggas Ajust prior to entering said chamber.

16. In an electric furnace for 'effecting vgas reactions the combination with a furnace chamber provided with an outlet for gases and an electrode extending into said charnber, of means for introducing a portionof the reaction gases at intermediate parts of tending through said tube into the furnace.

11.' The combination with an electric fursaid chamber and means for causing another portion of thev gases to contact with said electrode just prior to entering said chamber at one end thereof.

In testimony whereofI have hereunto set my hand in the presence of twov subscribing witnesses. Y M v Y p SVEND BARFOED. Witnesses:

JOHN H. HERRING, W. W. HEALEY. 

